New research from the Dunedin Study published in the International Journal of Obesity found an association between social jetlag (the difference in sleep pattern between work days and weekend), obesity and obesity-related disease including metabolic disorder, inflammation and diabetes.

The research found that individuals with a greater difference in sleep between free days and work days are more likely to be obese and suffer from obesity-related disease, than those with little to no difference between these timings. Unlike travel jetlag, which can cause temporary problems with metabolism, social jetlag can occur chronically throughout an individual’s working life so is more likely to induce more serious, chronic consequences for metabolism.

The lead author of this paper, Dr Michael Parsons from the Mammalian Genetics Unit at the UK Medical Research Council Harwell, said: “Social jetlag is an under researched but potentially crucial insight into the impact the idea of “living against our internal clock” is having on our health. Our research confirms a previous study that connected people with more severe social jetlag to increases in self-reported BMI, but this is the first study to suggest this difference in sleeping times can also increase the risk for obesity-related disease.”

This study clinically assessed the height, weight and waist circumference of participants in a controlled environment, as well as measuring C-reactive protein (hsCRP) and glycated haemoglobin in blood, biomarkers for inflammation and diabetes respectively. It then compared these findings with results from a questionnaire which assessed partipants sleep duration and chronotype, their preference in sleep timing. Researchers found just a two hour difference in sleep patterns on the weekend can increase your risk of an elevated BMI and biomarkers for inflammation and diabetes.

The reasons for this decline in immunity are unknown, but a possibility is that social jetlag disrupts healthy habits such as diet and exercise that may compromise health.

Dr Terrie Moffitt, co-author of the paper, added: “The findings of our study help us start to actually understand the physiology of social jetlag and how it impacts upon obesity and obesity-related disease. Further research that determines this association could help inform obesity prevention by influencing policies and practices that contribute to social jetlag, such as work schedules and daylight savings.”

This research was supported by the US National Institute of Ageing, the UK Medical Research Council, and the NZ Health Research Council.